1. Field of the Invention
The present invention relates to an erasable non-volatile semiconductor memory device, more particularly, to an erasable non-volatile semiconductor memory device having a plurality of memory cells each comprising two cell transistors and having a differential-type sense amplifier (differential amplifier).
2. Description of the Related Art
Recently, in accordance with a need for higher speed semiconductor integrated circuit devices, the realization of a higher speed has been demanded even in erasable non-volatile semiconductor memory devices (EPROM: Erasable Programmable Read Only Memory). Therefore, as such an EPROM where by a high speed reading operation is realized, it has been proposed that it be provided with a plurality of memory cells each comprising two cell transistors, and be able to read out the content of each of the memory cells by a differential type sense amplifier. An EPROM wherein this memory cell is constituted by two cell transistors, must be able to execute a test of the memory cells in a short time.